The aims of the proposed research are: first, to perceive the mechanisms by which constituent lipid molecules transfer between plasma lipoproteins and erythrocytes; and second, to search for changes in the physicochemical properties and biological function of the partners participating in lipid exchange in order to assess the consequences of interaction and of lipid transfer. This information will be sought by relating lipid transfer and lipoprotein-erythrocyte binding to lipoprotein structure and to the fluidity of lipoprotein and erythrocyte membrane, by determining the role of calcium ion in the lipoprotein-erythrocyte interaction, and by correlating alterations in cell morphology, fragility and in the molecular organization of the cell membrane with lipid transfer and lipoprotein binding.